We have proxy-server and I run Linux Mint 15 Mate. I've set up network connection and Firefox prompts for login/pass and then connects to Internet. When trying to look for updates/new software, system does not prompt for login/pass and cannot connect to Internet. What should be done to have system accessing Internet and getting updates/installing new software?
# man apt.conf ... .... http http::Proxy sets the default proxy to use for HTTP URIs ....
You need to edit config file: /etc/apt/apt.conf to configure APT package handling utility.
Additionally read about ProxyChains - redirect connections through proxy servers.
Package Manager -> Settings -> Network
Re-Enter your Proxy IP/Port and klick on
Authentication to set login/pass
How to find
Package Manager this could help: Mint: How to Open the Package Manager